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*range of ElectroMagnetic waves placed in order by decreasing  wavelengths. (ripples on water)

*Wave- anything that causes a disturbance and transmits energy thru matter or space.(light, sound, seismic)   

-way energy is carried away from source.  

-transfers energy as vibration occurs.

 -as wave travels-energy causes matter to move.

                  -medium- substance that wave travels through.

*EM waves are a form of energy that travels through space or matter.  ie: sunlight to earth

*Frequency- (# of waves in set time) decides energy.

                  -short wavelengths & high frequency= high energy

                  -long wavelengths & low frequency= low energy

                  - includes radio, microwave, infrared, visible light, ultraviolet light,  x-ray, & gamma rays.



*Visible light is narror range within the EM spectrum

                  -only waves we can see from the EM spectrum, rest invisible.

                  -made from colors (ROY G BIV), different wavelengths of light.

                  -longest wavelength-red; longest-violet, most energy.

                  -wavelengths affect the eye differently so we see different colors.

*Color- decided by absorbtion from object. Objects absorb color (hide) & reflect others (see)

                  -color seen is color reflected off object.

                  -reflect all color-white// absorb all color-black

                  -sunlight- mixture of colors

                  fyi: ozone layer- sunlight on oxygen molecules.

*White Light- when all colors are mixed. 

                  -visible light of all wavelengths of color combined.

                  -light enters and sent to retina (eye); 3 cones; red, blue, green;

                  all colors are absorbed of visible light-see white.

Eye (human’s) can distinguish millions of colors & hues.

                  -Prisms: white light in, color out due to bend of light by prism.

                                    seperates white light into parts.


Interaction of Light:      -when light hits an object it has 3 choices:

1. REFLECTION:   (bounces off)

                  *light hits an object that it can’t enter and so bounces off.   ie: mirror, sunglasses.

                  1.1. Regular reflection- same angles due to smooth surface.  ie: mirror.    Always equal.

                  1.1a. Angle of incidence- incoming rays and imaginary line perpendicular to surface. 

                  1.1b. Angle of reflection- reflected ray from light wave and imaginary line

1.2. Diffused reflection- rays scatter due to uneven or bumpy surface.

                                    *we see most objects because of scattering.


2.TRANSMISSION OF LIGHT:    (passes thru)

                  * Light usually travels in a straight line unless medium changes/bends it. In rays away from                   source.

                  *passing of light through matter (things that take up space-8CSS)

                                    -opaque-no light thru                                                        ie: wall

                                    -transparant-all light thru                                      ie: glass

                                    -translucent- some light thru                                      ie: wax paper                                   

*REFRACTION= change in speed & direction.

                  -when passing from one material to another it will change speed                   and  angle. 

                  -travels more slowly through certain medium (atoms-like diffusion)                 

                                     ie:  light travels faster in air than water

                  *light bends when changes from one medium to another.

                                    -changes direction when interacts with matter.

                                    -bend depends on wavelenghts (shorter-more bend).

                                    -bend of light due to change of speed.

                                    -light refracts once hits lens in eye; to retina. (camera)

                  * only see when light waves bounce off object, reflected or scattered, and into eyes.

                                    -medium not needed for light to move, part of EM Wave.



*ABSORPTION-   (enters)

                  * light absorbed by the material/medium that takes in the light holds it.

                  * transfer of energy by light waves to particles in matter.                  ie: dark material and pavement.

                                    black t-shirt in summer- hot due to holding light energy.

                  *light weakens as further from source- more matter absorbs it.

                                    -objects closer to the light are brighter than distant objects.

                                    -air particles absorb some light so gets dim the further away.


*SCATTERING-  (released)

                  *the  release of light energy by matter that absorbed extra energy.

                  *material decides what happens.

                  *light scatters in all directions once released.

                                    ie: can see outside of beam from flashlight.

                                    ie: sunlight throughout air.

                  sky is blue because blue is shorter wavelength and scattered more.


Lenses-  bends light rays

* Convex lens- thick middle and thin on edges                                    *Concave- thick outside and thin in middle

                   -bends parallel lines of light to focal point.                                    -spreads out parallel lines of light    -surface highly curved                                    no focus                  -converging lens                                                                                          -diverging lens                  -image larger and right-side up.                                                                        -image smaller and upright                  ie: eye, microscope, magnifying glass                                                      ie: glases to correct far-away vision



EM Spectrum - PH active art

Mirrors & Lenses - PH active art

Cow's Eye - PH active art